The invention also relates to a rotary roller having a jacketed working surface and a heat exchanger in a fluid heat transfer medium in an annular space immediately below the jacketed working surface, which heat exchanger comprises a system of ducts connected to a heating medium circulator.
The invention has been especially developed for use in the heat treatment of woven textiles, in particular felt and machine wires for use in the manufacture of paper. When treating felt for paper-making machines with the aid of oil-heated rollers, accurate control of the temperatures over the surface of the rollers is required.
GB-PS 1,513,732 makes known the heat treatment of woven textiles and other materials by using a rotating roller. Immediately below the jacketed working surface of the roller, provision is made for the presence of a fluid heat transfer medium which, with the aid of a heat exchanger inside the roller, can be heated as required. The heat exchanger is in the form of a system of ducts through which flows a heating medium, e.g., oil. As a heat transfer medium, a liquid is used which evaporates in a closed space that is heated via the heat exchanger, and where condensation occurs at cold points of the jacketed working surface. In this known roller, two different media are used as the heating medium and the heat transfer medium respectively.